Cover potatoes with water in a medium stock pot. Add salt and heat over high until boiling. Boil potatoes until very tender (10-15 minutes depending on their size). Drain and add back to pot.
While potatoes cook, place buttermilk and butter in a microwaveable bowl. Microwave on high until warm 30-60 seconds. Add warm buttermilk mixture, cream cheese, and seasoning to warm potatoes and coarsely mash with a potato masher to desired consistency.
Spoon potatoes into serving dish. Serve immediately or cover with foil and keep warm in a 250°F oven until ready to serve.